Rózsa Eva, Robotka Hermina, Vécsei László, Toldi József
Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary.
J Neural Transm (Vienna). 2008 Aug;115(8):1087-91. doi: 10.1007/s00702-008-0052-5. Epub 2008 Apr 30.
Kynurenic acid is an endogenous product of the tryptophan metabolism. Studies on the mechanism of its action have revealed that kynurenic acid at high concentrations is a competitive antagonist of the N-methyl-D-aspartate receptor and acts as a neuroprotectant in different neurological disorders. This in vitro investigation was designed to show that kynurenic acid acts differently at low concentrations. In vitro electrophysiological examinations on the young rat hippocampus confirmed the well-known finding that kynurenic acid in micromolar concentrations exerts an inhibitory effect. However, in nanomolar concentrations, kynurenic acid does not give rise to inhibition, but in fact facilitates the field excitatory postsynaptic potentials. The results available so far are compatible with the idea that kynurenic acid in the concentration range between a few hundred nanomolar and micromolar displays different effects. Its probable action on different receptors, inducing the different mechanisms, is discussed. The findings strongly suggest the neuromodulatory role of kynurenic acid under both physiological and pathological circumstances.
犬尿喹啉酸是色氨酸代谢的内源性产物。对其作用机制的研究表明，高浓度的犬尿喹啉酸是N-甲基-D-天冬氨酸受体的竞争性拮抗剂，在不同的神经疾病中起到神经保护剂的作用。这项体外研究旨在表明犬尿喹啉酸在低浓度时作用不同。对幼鼠海马体进行的体外电生理检查证实了一个已知的发现，即微摩尔浓度的犬尿喹啉酸具有抑制作用。然而，在纳摩尔浓度下，犬尿喹啉酸不会产生抑制作用，实际上反而会促进场兴奋性突触后电位。目前可得的结果与以下观点相符，即几百纳摩尔到微摩尔浓度范围内的犬尿喹啉酸会表现出不同的效应。文中讨论了其对不同受体可能产生的作用以及由此引发的不同机制。这些发现有力地表明了犬尿喹啉酸在生理和病理情况下均具有神经调节作用。
